This invention relates to sample collectors and components thereof. Some of the components have independent utility and are described in connection with sample collectors and in connection with other types of equipment and methods.
It is known to apply a protective coat to equipment such as sample collectors to protect the equipment from harmful environmental effects such as corrosion. In the prior art, most equipment such as refrigerated sample collectors, refrigerators, freezers and air conditioners are constructed by adding one part at a time into an integrated design with some of the parts already coated or painted. The prior art method has a disadvantage in that it is difficult to adequately seal all of the joints of the system. Moreover, when the system requires repair, the system must be dismantled, reassembled and an attempt made to provide a corrosive resistant coating in all of the joints and other inaccessible places.
It is known to provide a separate heating element and controls for a system to warm up a compressor prior to running the compressor in cold weather. This approach has the disadvantage of being expensive and requiring additional electrical insulative protection.
Peristaltic pumps are known which include a connecting band that is opened to obtain access to the peristaltic tube. In the prior art, the pumping action tends to flex the restraining element and causes wear on the tube. Moreover, it is difficult to unlatch the prior art bands and to re-latch them. This problem is particularly aggravated with peristaltic pumps having less than three rollers. With less than three rollers, for easy removal of the tube, more than 120° must be readily openable for inserting the tubing. Peristaltic pumps include a guideways for the pump tube leading to the raceway. In the prior art the shape of the guideways causes the tube to be moved from side to side and at times to rub against edges of the raceway under the stress of the paddle rollers.
In the prior art, generally geneva mechanisms or other apparatus are used to move the distributor arm. In order to obtain precision positioning, the units always hold the arm at a location that is known. However, this prevents the arm from being freely rotated when the waste water sampler is not operating. Prior art systems attempting to provide an indexing system that identifies the location of the distributor use multiple circles of indicia in multiple channels to indicate numerical position and direction of movement. These systems have the disadvantage of being complicated and expensive.